Allow your glass cooktop to cool completely before cleaning.
Add a quarter-sized drop of glass cooktop cream cleaner to the gray marks.
Use the razor scrapper to scrape off the gray marks, using slight pressure as you move around the marks. Hold the tool at a 45-degree angle. To avoid scratches, keep some cleaner between the glass cooktop and the razorblade the entire time you're cleaning.
Clean away any remaining cleaner and residue from the razorblade with a paper towel.
Apply more cleaner over various spots on the cooktop and spread it around the entire surface, using a clean paper towel. Rub the surface with gentle, circular motions. Wipe away excess using a second paper towel or clean cloth.